Fission Stories #84: It’s Hammer Time!

A worker operator with an ax reportedly played an important, although passive, role in the first nuclear chain reaction at the University of Chicago in December 1942. Urban legend traces the origins of the “reactor scram” term to the Single Control Rod Ax Man (SCRAM). The oft-told story has a worker armed with an ax ready to cut the rope holding the safety control rod withdrawn from the pile of graphite and uranium. Gravity would drop the control rod into the pile, interrupting the nuclear chain reaction.

Half a century later, modern nuclear power plants supply electricity to millions of homes and businesses. The ax man has long been replaced with a guy with a hammer, at least at two nuclear plants.

In 1987, the emergency equipment needed to cope with a nuclear accident at the Sequoyah nuclear plant in Soddy-Daisy, Tennessee included a hammer. This hammer, stored in a special wooden box just outside the control room, would be used by operators in case of an earthquake to protect themselves against radiation.

Analyses had indicated that the water in the plumbing lines from the toilets in the rest rooms next to the control room might spill or drain out if there was an earthquake. Without the water seals, the hollow plumbing pipes could allow radioactive gases to flow into the rest room and then into the control room. To protect the operators from this potential radiation hazard, the emergency procedures for responding to an earthquake directed the operators to use the hammer to smash the toilets. Duct tape, also stored in the wooden box, would be used to cover the hole in the floor.

Knowing the nuclear industry’s fondness for redundancy and defense-in-depth, there were probably two wooden boxes each containing a hammer and a roll of duct tape. Or, perhaps one wooden box containing two hammers and two rolls of duct tape. Knowing the nuclear industry’s penchant for extensive training, there were probably quarterly drills. Instead of the duck and cover drills of the 1960s, these were cover and duct drills.

In 1992, the Nuclear Regulatory Commission fined the owners of the Point Beach nuclear plant in Wisconsin $150,000. It seems that the main steam isolation valves had a long history, dating back to the early 1970s, of not closing properly. These valves—which are normally open when the plant is operating to allow steam to pass from the steam generators to the main turbine—must close under certain accident conditions to prevent radioactive gases from flowing to the environment. NRC inspectors discovered that “plant personnel routinely used a sledge hammer to jar the valves if they did not close upon demand during routine shutdowns.”

The NRC was upset because these valves were required to automatically close, yet from tests in 1987, 1989, 1990, and 1991 the plant’s owners knew that some valves would not close without “encouragement” from the sledge hammer. Following an accident, the worker with the sledge hammer might not be quick enough to whack away and close the valves in time to protect the public.

Our Takeaway

Oh, to be a fly on the wall during the meeting where management first showed the control room operators the hammer and duct tape they’d need for radiation protection during an accident. Any manager surrendering the hammer to an operator’s seemingly innocent request to see it probably deserved having his bell rung.

However, the Sequoyah case does illustrate the depth and breadth of the “what if” scenarios considered when planning emergency responses. While every possible contingency cannot be anticipated, these accounts suggest there’s a strong foundation laid for developing ad hoc responses during actual emergencies.

There’s no excuse for the antics at Point Beach. The sustained, recurring practice of applying “mechanical agitation”—the nuclear industry’s term of art for whacking away at a stubborn component—to get vital valves to close is indefensible. The practice over so many years had to have involved numerous workers and supervisors. Someone at some time should have thrown the flag to halt this nonsense. Ultimately, the NRC threw the flag, wrapped in a ticket for $150,000.

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